Such a technology is disclosed in Japanese Patent Application Laid-Open Publication No. 2006-125098. This conventional keyless device of a vehicle has a vehicle interior transmitting antenna that transmits an answer request signal to an interior of the vehicle, and a vehicle exterior transmitting antenna that transmits an answer request signal to an exterior of the vehicle. When a door operator, such as a driver, approaches the vehicle with a portable device to enter a vehicle exterior detection area and touches an outer door handle, an identification verification routine signal is sent to a main electric control unit (ECU), the vehicle-interior transmitting antenna and the vehicle-exterior transmitting antenna transmit the answer request signals. When these signals are received by the portable device, the portable device sends information on a specific identification (ID). The information is received through the vehicle exterior transmitting antenna by the main ECU, and all of door locks are released when the main ECU verifies the coincidence with the ID codes.
When the driver opens a door to ride in the vehicle and pushes an ignition knob, the portable device and the main ECU verify the coincidence of the ID code through the vehicle exterior transmitting antenna. The coincidence of the ID codes being verified, a rotational operation of the ignition knob causes the engine to start without using a mechanical key.
The conventional keyless device, however, has a problem in that, in a case where the vehicle interior antenna malfunctions, the driver cannot start the engine by operating the ignition knob, because the existence of the driver with the portable device cannot be detected in the interior of the vehicle.
The present invention is made to solve the above-described problem, and its object is to provide a keyless device of a vehicle that can detect a portable device that is located in an interior of the vehicle in a case where a malfunction occurs in a vehicle interior antenna for transmitting an answer request signal to the portable located in the interior of the vehicle.